David Rosnick is an economist at the Center for Economic and Policy Research, in WashingtonD.C.

CEPR

Adjusting for Polling Biases in

Venezuela’s 2012 Presidential Election

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Executive Summary

This paper uses polling data from the various polling firms in Venezuela over the years 2004-2010 toadjust the most recent polling data for polling firm bias in past elections. The regression resultsshow that the average lead of President Hugo Chávez over challenger Henrique Capriles movesfrom 11.7 percentage points (unadjusted) to a 13.7 percent (adjusted) lead. This would give Caprilesa 5.7 percent probability of winning the election. The adjustment employs a constrained regression model to take into account the bias of participation of the firm in each of the election years that make up the data set (2004, 2006, 2007,2009, and 2010). The results are robust to excluding any one of the years from the constraint, withthe probability of an opposition win ranging from 3.1 to 9 percent, depending on which year is notpart of the constraint.

Introduction

According to recent polling of the Venezuelan electorate

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, incumbent president Hugo Rafael ChávezFrías is expected to win by an average of 11.7 points

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with pollsters reporting results anywherefrom a 19.7 point victory (IVAD) to a 0.8 point loss (C21). But not all polls have the same track record over the previous five elections that took place between 2004 and 2010, and it may help to

adjust the various poll results for “house” bias of the polling firm.

Determining the house bias is a tricky matter. Bank of America’s Francisco Rodriguez r

eleased ashort report last month that found Chávez with a 15.9-point lead after adjusting for polling

companies’ biases, based on their track records.

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More recently, Iñaki Sagarzazu reported a muchcloser result

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only six points.

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This paper seeks to help sort out the current polling results.

Historical Poll Results

Figure 1

shows the average polling error for eight different polling companies. A positive errorimplies that a poll reported better performance on the part of the government than the actualelection results indicated. Thus, a positive error may indicate pro-government bias, or equivalently that the government under-performed in the election.It would appear that the opposition outperformed relative to the polling of 30.11 Consultores, forexample. However, we have historical data for this polling company in only 2006 and 2007

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years in which the government slightly underperformed relative to the average poll. This is seen in

Figure 2

,below.

1 Based on the most recent surveys conducted between August 25 and September 25.2 Rodriguez (2012).3 Sagarzazu (2012).